Accessing external memory

I have to find the address of a file stored in SD card

Say what?

I want to know how to find the address of a file stored in the flash memory of the SD card..will pointer concept be useful??? If there are 3 or 4 files stored i want to get the location of each file...

The normal meaning of external memory, is direct-access code or data memory outside the processor.

Not a serially connected SD-card that you handle similar to a hard disk, by formatting it and reading/writing sectors of data.

So you need to learn how to read sectors of data from that SD card.
And how to detectt if the card is formatted with a file system you understand.
Then evaluate the contents of the data structures on the file system, to figure out where the file is stored.

Most people just buy a file system implementation, or look for one freely available implementation. Then they don't care about the actual storage location of files on the card - it's enough to be able to fopen() the file for fseek()/fread()/fwrite(), or unlink() it.

But your project must be better specified than what you managed to present in your original post. And if it's _your_ project, the goal must somehow be for _you_ to do the task or it wouldn't be your project, would it?

i have just started to work on it... thank you for your note....will read about reading sectors...

I am presently working on accessing external memory. For my project, I have to find the address of a file stored in SD card.

You didn't get what the first responder was trying to tell you. You're mixing apples and oranges there.

An SD card is not what the term "external memory" refers to. Not in modern-day microcontrollers anyway, where memory is usually internal to the chip, so external memory would be RAM or ROM connected directly to the controller. An SD card is mass storage. Whole different kettle of fish.